WASHINGTON — By the light of the silvery moon, corals get in tune, and soon, it's a spawning delight.

While that silvery moon was written about people, the songwriter understood the motivation.

Now, scientists think they may have found out how reef-building corals manage to coordinate their sex lives in moonlight bay.

In late spring it's reef madness as corals release sperm and eggs into the water for a few nights after a full moon.

But how do they know?

Researchers led by Oren Levy of the Center for Marine Studies at the University of Queensland, Australia, studied corals on Australia's Great Barrier Reef.

They report in Friday's issue of the journal Science that while corals don't have eyes they are able to sense changes in light — especially blue light — and respond to them. The corals contain ancient proteins called cryptochromes which react to light. Cryptochromes have also been found in mammals and insects where they effect the circadian clock that regulates the daily rhythms of life.

This finding indicates that the basic means used by mammals today to regulate daily patterns was in use at the beginnings of multicellular animals, the researchers said. And, they added, it supports the idea that these proteins evolved under the blue light of the ancient seas.

The research was funded by the Marie Curie International Outgoing Fellowship and the ARC Center for Excellence in Coral Reef Studies.

Copyright 2007 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.